Piston scraper localisation system in pipeline - uses transceiver outside pipe and transceiver in pipe operating on 20 Hz frequency

摘要

The pipeline cleaning piston locating system has a first circuit(3) which is fitted to the piston(2) in the pipeline. This first circuit(3) includes an alternating signal receiver and a reference alternating signal transmitter. The signal frequencies being less than 100Hertz, pref. less than 20 Hertz. The transmitter circuit is normally switched off, but is actuated by the incoming signal to the receiver. Thus the transmitter circuit transmits when the receiver circuits receives an exterior signal. A second circuit(4) exterior to the pipeline(1) includes a transmitter which emits a signal in the direction of the pipeline. This second circuit has also a receiver for receiving the reference signal emitted by the first circuits transmitter. The first circuits transmitter includes a emission coil coaxial with the pipeline. The first circuits transmitter and the second circuits receiver each include a coil having parallel axes.